The purpose of proposed research is to characterize antibody-independent immunity to malaria in B-cell deficient animals and to define the mechanisms involved. Mice and chickens will be rendered B-cell deficient by means of anti-u suppression and combined chemical bursectomy respectively. Immunization will be achieved by infecting mice with P. yoelii and chickens with P. gallinaceum. Acute infections will be terminated by means of drug therapy. Such animals fail to develop recurrent disease and resist challenge infection with homologous plasmodia. In the proposed study the specificity of antibody-independent immunity will be determined by testing the ability of immunized animals to resist challenge with heterologous plasmodia. This form of immunity will be further characterized ragarding its duration and strength. The contributions of macrophages and T-lymphocytes to antibody-independent immunity will be assessed in poisoning and adoptive transfer studies respectively. The latter will utilize a unique immunologic deficient host, the B-cell deficient nude mouse. Finally, an attempt will be made to correlate mononuclear chemotactic factor with antibody independent immunity to malaria and to determine if such immunity functions in the immunologically intact host.